Inside a cabin of a hydraulic excavator such as a working machine, various kinds of instruments are provided to enable an operator to confirm basic information on a vehicle body state of the hydraulic excavator. These kinds of instruments include, for example, a coolant temperature indicator, a working oil temperature indicator, a residual available fuel level indicator, and an engine speed indicator. An hour-meter that indicates an elapsed total operation time of the hydraulic excavator, an instrument that indicates information on the selector position of a gate lock lever, and other information indicators may also be provided as appropriate.
In recent years, various information on a specific hydraulic excavator, including the information that the above-mentioned instruments acquire, has come to be displayed collectively on a display monitor such as a liquid-crystal display. During normal vehicle operation, a temperature of a coolant, a residual available fuel level, and other basic information on the vehicle body state are displayed on such a monitor. However, for example if an abnormality occurs in the hydraulic excavator, warning information on the occurrence of the abnormality, the kind and details thereof, a necessary remedial action against the abnormality, and the like, needs to be displayed to notify the abnormality to an operator.
Additionally, since a sufficient rearward vision cannot be ensured for the operator who operates the machine from the cabin, the hydraulic excavator may have a supervisory camera at a rear position thereof to display a camera image on the monitor. This ensures the operator's auxiliary rear visibility, enabling safe working.
It is preferable that such a monitor be as compact as possible to ensure the operator's view. In addition, the volume of information to be displayed tends to increase with the functional diversification of hydraulic excavators in recent years. It is therefore necessary for the monitor to display a larger volume of information more efficiently in a limited display region.
In other words, while basic information needs to be displayed at all times, warning information does not need to be displayed in usual operation. But in case of an abnormality, it is necessary to make such a display that the operator can reliably recognize warning information. At the same time, the two kinds of information needs to be switched and displayed in an efficient manner.
Patent Document 1 discloses two techniques as prior art for displaying basic information under a normal state and warning information under an abnormal state. The first of the two techniques is designed so that a warning icon is activated in case of an abnormality and so that the display of the basic information is switched to that of character information relating to details of the warning icon. The second of the two techniques is designed so that in case of an abnormality, character information relating to details of a warning icon is displayed in overlapped form on the basic information.